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Abstract:

The invention relates to a recording material for electrophotographic
printing processes, that comprises a carrier material, a metal coated
plastic film and a toner-absorbing layer, and which is suitable for
producing images of near-photographic quality using both dry and liquid
toners.

Claims:

1. Recording material for electrophotographic printing processes,
comprising a carrier material and at least one toner-absorbing layer,
wherein the recording material contains a plastic film arranged between
the carrier material and the toner-absorbing layer, and coated with a
metal.

2. The recording material of claim 1, wherein the metal has an electrical
conductivity not exceeding 40.times.106 S/m.

3. The recording material of claim 2, wherein the metal is aluminium.

4. The recording material of claim 3, wherein the plastic film is a
multilayer, biaxially oriented polypropylene film.

5. The recording material of claim 4, wherein the metal-coated side of
the plastic film has a specific roughness, expressed by the roughness
value Rz, from 0.01 to 2 μm.

6. The recording material of claim 1, wherein the rear side of the
carrier material has a resin layer.

7. The recording material of claim 6, wherein the resin layer is an
extruded polyolefin layer or a polymer film that is laminated on.

9. The recording material of claim 8, wherein the binder that is
dispersible in water is an ethylene acrylate polymer or an ethylene
acrylate copolymer.

10. The recording material of claim 9, wherein the finely particulate
inorganic pigment is aluminium oxide, aluminium oxide hydrate, silicic
acid, an oxide of antimony, indium, titanium, zinc or tin, or a mixed
oxide of two or more of these elements.

11. The recording material of claim 10, wherein the finely particulate
inorganic pigment has an average particle size from 10 nm to 2 μm.

12. The recording material of claim 11, wherein the finely particulate
inorganic pigment has a BET surface area of 10 m2/g to 400
m2/g.

14. The recording material of claim 8, wherein the conductive component
is an electrically conductive polymer.

15. The recording material of claim 8, wherein the quantity of the
electrically conductive component in the toner-absorbing layer is from 0
to 50% by weight, particularly 0.1 to 4.0% by weight, relative to the
mass of the dried layer.

16. The recording material of claim 1, wherein the carrier material is a
base paper or a coated base paper.

17. The recording material of claim 6, wherein the surface resistivity of
the recording material is less than 15 (Ohm/cm), measured in accordance
with DIN 53483.

18. Recording material for electrophotographic printing processes,
comprising a carrier material and at least one toner-absorbing layer,
wherein the recording material contains a plastic film arranged between
the carrier material and the toner-absorbing layer, and coated with a
metal, to provide a metal-coated side, wherein: a) the metal is aluminium
and has an electrical conductivity not exceeding 40.times.106 S/m, b) the
plastic film is a multilayer, biaxially oriented polypropylene film, c)
the metal-coated side of the plastic film has a specific roughness,
expressed by the roughness value Rz, from 0.01 to 2 μm, and d) the
rear side of the carrier material has a resin layer, wherein the resin
layer is an extruded polyolefin layer or a polymer film that is laminated
on.

19. A recording material of claim 18, wherein: a) the toner-absorbing
layer contains a binder that is soluble and/or dispersible in water, a
finely particulate inorganic pigment and/or an electrically conductive
component, b) the binder is an ethylene acrylate polymer or an ethylene
acrylate copolymer, c) the finely particulate inorganic pigment is
aluminium oxide, aluminium oxide hydrate, silicic acid, an oxide of
antimony, indium, titanium, zinc or tin, or a mixed oxide of two or more
of these elements, d) the finely particulate pigment has an average
particle size from 10 nm to 2 μm and a BET surface area of 10
m2/g to 400 m2/g, and wherein the electrically conductive
component is a finely particulate, electrically conductive pigment.

20. A recording material of claim 18, wherein: a) the toner-absorbing
layer contains a binder that is soluble and/or dispersible in water, er,
a finely particulate inorganic pigment and/or an electrically conductive
component. b) the binder is an ethylene acrylate polymer or an ethylene
acrylate copolymer, c) the finely particulate inorganic pigment is
aluminium oxide, aluminium oxide hydrate, silicic acid, an oxidc of
antimony, indium, titanium, zinc or tin, or a mixed oxidc of two or more
of these elements, and d) the finely particulate pigment has an average
particle size from 10 nm to 2 μm and a BET surface area of 10
m2/g to 400 m2/g, and wherein the electrically conductive
component is an electrically conductive polymer, wherein the quantity of
the electrically conductive component in the toner-absorbing layer is
from 0 to 50% by weight, particularly 0.1 to 4.0% by weight, relative to
the mass of the dried layer, wherein the carrier material is a base paper
or a coated base paper, and wherein the surface resistivity of the
recording material is less than 15 (Ohm/cm), measured in accordance with
DIN 53483.

Description:

FIELD OF THE INVENTION

[0001] The invention relates to a recording material with which images may
be produced in photographic quality with electrophotographic printing
processes.

BACKGROUND OF THE INVENTION

[0002] The laser printer is based on the principle of electrophotography.
In electrophotography, a latent image is generated from electrical
charges by irradiating or exposing a photo-conductor with the optical
copy of an image, and this image is subsequently used to apply a toner
selectively (development) and generate a reproduction (copy) of the image
on paper, for example. A distinction is made between direct and indirect,
and also wet and dry electrophotography. The wet processes, also called
liquid toner processes, use a suspension of an aliphatic solvent with a
low dielectric constant and the toner as the developer, whereas the dry
process employs a powder. A copy of the desired page is marked on the
light-sensitive drum using a concentrated laser beam and a rotating
mirror. The drum is negatively charged initially, but the charge is
neutralised at the points where the laser beam exposes the photoconductor
surface. The shape of the surface areas from which the charge has been
removed corresponds to the subsequent printed output. The toner is
applied to the drum via a roller with negatively charged toner, which
sticks to the sites on the drum that do not carry a charge.

[0003] In the dry process, the paper is then passed over the drum. It
merely slides past the drum. A potential field is formed behind the
paper. The toner is transferred to the paper, where it is initially
loose. Then, the toner is fixed using a hot roller and pressure. The
charge is drained from the drum and excess toner is removed from it.

[0004] In the liquid toner process the toner suspension is first
transferred to a heated rubber cylinder, on which the carrier liquid is
evaporated and the toner is plasticised. From this intermediate drum, the
toner image is then transferred to the image receiving sheet.

[0005] The images created using a laser printer should attain a quality
comparable with a photograph. Properties to be considered for this
purpose include gloss, stiffness, opacity, high resolution and image
definition, and good resistance to light.

[0006] The publication by HP (Hannelore Breuer): Das Know-how des
Druckens: Die neuen Laser-Papiere (English: Expertise in printing: The
new laser papers) dated May 13, 2005, available under
41131.www4.hp.com/Backgrounder_Neue_Laser-Papiere.pdf (last updated on
Aug. 31, 2010) describes papers with multilayer coatings and an "open"
porous surface on both sides. However, the texture of images reproduced
using these papers differ considerably from conventional silver halide
images and their gloss and surface are also quite dissimilar.

[0007] In order to get closer to the objective of near-photographic
quality, electrophotographically created images are produced on carrier
materials that have the same haptic properties and appearance as a
typical silver salt photograph. An image receiving material for
electophotography that comprises a base paper coated with a thermoplastic
resin, a toner receiving layer and an antistatic rear side layer is
described in document DE 44 35 350 C1. The disadvantage of this material
is that it is still not ideal with regard to toner fixing and its
behaviour in the printer. Moreover, after an image has been printed such
materials exhibit shiny patches, originating from the oily substances
frequently used as releasing agents in the toner formulas.

[0009] It is therefore the object of the invention to provide a recording
material that is printable from at least one side, has good image
quality, comparable with that of a silver salt photograph, and besides
being resistant to light and ozone during storage also has good pickup
and transport behaviour in the printer and lends itself well to stacking.

[0010] This object is solved with a recording material having a carrier
material and at least one toner-absorbing layer, wherein the recording
material includes a plastic film that is coated with a metal and
positioned between the carrier material and the toner-absorbing layer.

[0011] The metals used for coating the plastic film are preferably metals
with an electric conductivity of not more than 40×106 S/m.
Electrical conductivity describes the capability of a substance to
conduct electric current, the reciprocal value of which is specific
resistance. Aluminium is particularly well suited for this purpose.

[0012] The plastic film suitable for coating with the metal may be a
polyolefin film, for example a polyethylene or polypropylene film. It may
have a monolayer or multilayer structure. Preferably, a multilayer,
biaxially oriented polyolefin film particularly a polypropylene film is
used. The polyolefin film preferably includes a porous core layer and at
least one essentially non-porous surface layer disposed on at least one
side of the core layer.

[0013] The metal-coated plastic film may preferably have a thickness from
10 to 50 μm. The metal-coated plastic film preferably has an opacity
greater than 98% and a specific surface topography, expressed by a
roughness value Rz from 0.01 to 2 μm.

[0014] The carrier material may be an uncoated base paper, a coated base
paper (base paper provided with a pigment-containing layer) or a
resin-coated paper.

[0015] The toner-absorbing layer may preferably contain a binder that is
soluble and/or dispersible in water, a finely particulate, oil absorbing
pigment and/or an electrically conductive component, wherein the
electrically conductive component may be a finely particulate
electrically conductive oxide or an electrically conductive polymer.

DETAILED DESCRIPTION OF THE INVENTION

[0016] For the purposes of the invention, the term base paper is used to
refer to an uncoated or surface-sized paper. Besides cellulose fibres, a
base paper may contain sizing substances such as alkyl ketene dimmers,
fatty acids and/or fatty acid salts, epoxidised fatty acid amides,
alkenyl or alkyl succinic acid anhydride, wet strengthening agents such
as polyamine-polyamide-epichlorhydrin, dry strengthening agents such as
anionic, cationic or amphoteric polyamides or cationic starches, optical
brighteners, bulking agents, pigments, dyes, antifoaming agents, and
other auxiliary substances known in the paper industry. The base paper
may be surface sized. Sizing substances suitable for this purpose include
for example polyvinyl alcohol or oxidised starch. The base paper may be
produced on a Fourdrinier or a Yankee paper machine (cylinder paper
machine). The grammage of the base paper may be from 50 to 250 g/m2,
particularly from 80 to 180 g/m2. The base paper may be used in
uncompacted or compacted form (finished). Base papers having a density
from 0.8 to 1.2 g/cm3, particularly 0.90 to 1.1 g/cm3, are
particularly suitable. Cellulose fibres may be obtained for example from
laubholz bleached kraft pulp (LBKP), northern bleached kraft pulp (NBKP),
laubholz bleached sulphite pulp (LBSP) or northern bleached sulphite pulp
(NBSP). Cellulose fibres recovered from paper waste may also be used. The
cellulose fibres listed in the preceding may also be used together in
mixtures and fractions of other fibres, resin fibres for example, may be
added to the mixture. However, cellulose fibres from 100% laubholz
cellulose are preferred. The average fibre length of the unrefined
cellulose is preferably 0.6 to 0.85 mm (Kajaani measurement). The
cellulose also has a lignin content of less than 0.05% by weight,
particularly from 0.01 to 0.03% by weight, relative to the mass of the
cellulose.

[0017] Bulking agents used in the base paper may include for example
kaolin, calcium carbonate in its natural forms, such as lime-stone,
marble or dolomite stone, precipitated calcium carbonate, calcium
sulphate, barium sulphate, titanium dioxide, talcum, silica, aluminium
oxide and mixtures thereof. Calcium carbonate having a grain size
distribution in which at least 60% of the particles are smaller than 2
μm and not more than 40% are smaller than 1 μm is particularly
suitable. In a particular embodiment of the invention, calcite with a
grain size distribution in which about 25% of the grains have a grain
size smaller than 1 μm and about 85% of the particles have particle
size less than 2 μm.

[0018] In a particular embodiment of the invention, a pigment-containing
layer may be applied to the base paper. The pigment may be a metal oxide,
silicate, carbonate, sulphide or sulphate. Pigments such as kaolin,
talcum, calcium carbonate and/or barium sulphate are particularly
suitable. Particularly preferred is a pigment with a narrow grain size
distribution in which at least 70% of the pigment particles are smaller
than 1 μm. The fraction of the pigment with such narrow grain size
distribution as part of the total pigment quantity is at least 5% by
weight, particularly 10 to 90% by weight. Particularly good results may
be obtained if the amount of pigment having the narrow grain size
distribution accounts for 30 to 80% by weight of the total pigment
quantity. According to the invention, pigments with a narrow grain size
distribution are also understood to include pigments with a grain size
distribution in which at least about 70% by weight of the pigment
particles are smaller than about 1 μm and the difference between the
pigment with the largest grain size (diameter) and the pigment with the
smallest grain size is less than about 0.4 μm in 40 to 80% by weight
of these pigment particles. A calcium carbonate with a d50% value of
about 0.7 μm proved particularly advantageous.

[0019] In a further embodiment of the invention the pigment-containing
layer may contain a pigment mixture that is constituted of the calcium
carbonate and kaolin referred to in the preceding. The calcium
carbonate/kaolin ratio is preferably 30:70 to 70:30. The binding
agent/pigment ratio in the pigment containing layer may be from 0.1 to
2.5, preferably 0.2 to 1.5, but particularly about 0.9 to 1.3. Any known
binding agent that is soluble and/or dispersible in water may be used in
the pigment containing layer. Besides latex binders, binding agents that
are particularly suitable for this include film-forming starches such as
thermally modified starches, particularly corn starches or
hydroxypropylated starches. The pigment-containing layer may be applied
inline or offline using any standard application units in the paper
manufacturing industry, and the application quantity is selected such
that after drying the coating weight is 0.1 to 30 g/m2, particularly
1 to 20 g/m2, or according to a particularly preferred embodiment 2
to 8 g/m2. In a preferred embodiment, the pigment-containing layer
is applied using a size press or film press that is integrated inside the
paper machine.

[0020] In another embodiment of the invention, layers of resin may be
provided on both sides of the base paper or coated base paper. The resin
layers (front and/or rear resin layer) may preferably contain a
thermoplastic polymer. Particularly suitable for this are polyolefins,
for example low density polyethylene (LDPE), high density polyethylene
(HDPE), poly-propylene, 4-methylpentene-1 and mixtures thereof, also
poly-esters, for example polycarbonates. In a particular refinement of
the invention the thermoplastic polymer is a biodegradeble polymer and/or
a polymer based on renewable raw materials such as a linear polyester,
thermoplastically modified starch, or polylactic acid or a mixture of
these polymers with each other or with other polymers.

[0021] In a further particularly preferred refinement of the invention the
resin layer on front and/or rear side contains at least 40% by weight,
particularly 60 to 80% by weight HDPE with a density greater than 0.95
g/cm3. A particularly preferred composition consists of 65% by
weight HDPE with a density greater than 0.95 g/cm3, and 35% by
weight LDPE with a density lower than 0.935 g/cm3.

[0022] The resin layers may contain white pigments such as titanium
dioxide and additional auxiliary agents such as optical brighteners, dyes
and dispersing agents. In a particular embodiment of the invention,
antistatic substances, particularly electrically conductive inorganic
pigments, are added to the resin layers.

[0023] The coating weight of the resin layers may be 5 to 50 g/m2,
particularly 5 to 30 g/m2, but preferably 10 to 20 g/m2. The
resin layer may be extruded or co-extruded in multiple layers onto the
base paper or coated base paper. Extrusion coating may be carried out at
machine speed up to 600 m/min.

[0024] In one embodiment of the invention, the resin layers may be applied
symmetrically to both sides of the base paper, that is to say the resin
layers on both sides of the base paper have the same composition and are
identical with regard to surface topography. According to the invention,
the surface of the resin layer on both sides may have roughness values Rz
from 0.03 to 15 μm. Roughness Rz is determined in accordance with DIN
4768 using a Hommel surface scanner.

[0025] In a further embodiment of the invention, the objective of which is
to produce a glossy recording material that is printable on one side, the
resin layer on the side of the recording material that supports the
toner-absorbing layer and that is intended to receive the printing (front
side) is less rough than the resin layer on the rear side. In this
embodiment, the resin layer on the side intended to receive the printing
has roughness values Rz from 0.03 to 1.8 μm, whereas the resin layer
on the side that is not intended for printing has roughness values Rz
from 12 to 16 μm.

[0026] According to the invention, a metal-coated plastic film is first
applied by lamination to the side of the carrier material, particularly a
base paper or coated base paper, that is intended for printing. In this
context, a polymer layer, preferably low density polyethylene (LDPE), is
extruded between the carrier material and the plastic film. The thickness
of the polyethylene layer is 6 to 15 g/m2, particularly 6 to 10
g/m2.

[0027] According to the invention, the metal-coated plastic film may be
laminated onto one or both sides of the carrier material. In the
embodiment of the invention according to which the metal coated plastic
film is only positioned on one side of the carrier material, the rear
side of the carrier material may be coated within an extruded
thermoplastic polymer. Particularly suitable for this are polyolefins,
for example low density polyethylene (LDPE), high density polyethylene
(HDPE), polypropylene, 4-methylpentene-1 and mixtures thereof, also
polyesters. The coating weight of the polymer layer on the rear side may
be 5 to 50 g/m2, particularly 5 to 30 g/m2. In a further
embodiment of the invention a monolayer or multilayer plastic film,
particularly a biaxially oriented polypropylene film may be applied to
the rear side. The core layer may be covered on either side by
essentially non-porous surface layers.

[0028] In the next step, a toner-absorbing coating solution is coated onto
the metal-coated side of the film that is applied to the carrier
material, and after drying this forms the toner-absorbing layer. In the
particular version of the invention that is designed to produce a
recording material that is printable on both sides, the metal-coated
plastic film and the toner-absorbing layer applied to both sides of the
carrier material.

[0029] The toner-absorbing layer preferably contains at least one binder
that is soluble and/or dispersible in water, a finely particulate pigment
and/or an electrically conductive component.

[0030] The binder in the toner-absorbing layer may be any binder in
standard use for paper coatings, the preferred binder substances being
starch, polyvinyl alcohol, acrylates or copolymers of acrylates with
other monomers. Particularly preferred binders are ethylene acrylic acid
copolymers, particularly those that with a melting point between 70 and
100° C.

[0031] According to the invention, the finely particulate pigment in the
toner absorbing layer is a finely particulate inorganic pigment, for
example silicon dioxide, aluminium oxide, aluminium oxide hydrate,
aluminium silicate, calcium carbonate, zinc oxide, tin oxide, antimony
oxide, titanium dioxide, indium oxide or a mixture of these oxides. In a
particularly preferred embodiment, the finely particulate pigment is zinc
oxide, tin oxide, antimony oxide, titanium dioxide, indium oxide or
mixture of these oxides. The finely particulate pigments may be present
in the toner-absorbing layer alone or as mixtures.

[0032] The finely particulate pigments in the toner-absorbing layer
preferably have an average particle size smaller than 1000 nm,
particularly smaller than 200 nm. Pigments with a BET surface area from
30 m2/g to 400 m2/g are particularly preferred. Pigments
according to the invention may be obtained by the flame method or by wet
chemical precipitation processes.

[0033] According to the invention, the electically conductive component in
the toner-absorbing layer may be an electrically conductive polymer
and/or an electrically conductive pigment. Electrically conductive
polymers according to the invention may be such in which the electrical
charge is transported in the form of ions, such as polystyrene sulphuric
acid. However preference is given to polymers, in which the electrical
charge is transported in the form of electrons or electron holes, for
example polyanilines and polythiophenes. A substance that is particularly
preferred as a conductive polymer is poly(3,4-ethylene-dioxythiophene)
doped with polystyrene acid (PEDOT:PSS), and which is available
commercially under the names CLEVIOS® or ORGACON® for example. If
a polymer is used as the electrically conductive component in the
toner-absorbing layer in accordance with the invention, in a particular
variation of the invention it may replace some or all of the
water-soluble or water-dispersible binder.

[0034] Conductive pigments according to the invention may be made up of
metal powder or carbon, among other components. However, oxides such as
antimony oxide, tin oxide, indium oxide, or particularly preferably
titanium dioxide or zinc oxide, of oxide mixtures of the elements
antimony, indium, titanium, zinc or tin are preferred. The conductive
pigments according to the invention preferably have an average particle
size smaller than 1000 nm, particularly preferably smaller than 200 nm.
If a conductive pigment is used as an electrically conductive component,
in a preferred embodiment of the invention it may also be the finely
particulate pigment of the toner-absorbing layer.

[0035] The quantity of the electrically conductive component in the
toner-absorbing layer is selected such that the surface resistivity of
the recording material is less than 15 log (Ohm/cm), measured according
to DIN 53483. According to the invention, it may lie in a range from 0 to
50% by weight, particularly 0.1 to 4.0% by weight, relative to the mass
of the dry layer.

[0036] In a further variation of the invention, the toner-absorbing layer
also contains anionic or non-ionic surfactants in a quantity of 0.01 to
4.0% by weight, particularly 0.05 to 2.5% by weight relative to the dried
layer.

[0038] The coating compound for forming the toner-absorbing layer may be
applied inline or offline using any of the application equipment commonly
used in such processes, wherein the quantity is selected such that the
coating weight after drying does not exceed 3 g/m2, particularly 0.1
to 2 g/m2, or according to a particularly preferred embodiment, 0.3
to 0.7 g/m2. The coating compound may be spread on with the aid of a
standard coating mechanism integrated in the extrusion coating system. A
3-roller application is particularly suitable for this purpose, or a
squeegee device.

[0039] In a further embodiment of the invention, further layers such as
protective layers or gloss enhancing layers may be applied over the toner
absorbing layer. The coating weight of such layers is preferably less
than 1 g/m2.

[0040] The invention will be explained in greater detail with reference to
the following examples.

EXAMPLES

[0041] A base paper A was produced from eucalyptus pulp. For refining, the
pulp was placed in a roughly 5% aqueous suspension (thick matter) and
ground to a degree of fineness corresponding to 36° SR with the
aid of a refiner. The average fibre length was 0.64 mm. The concentration
of cellulose fibres in the thin matter was 1% by weight relative to the
mass of the cellulose suspension. Additives were added to the thin
matter, including cationic starch in a quantity of 0.4% by weight, alkyl
ketene dimer (AKD) as a neutral sizing agent in a quantity of 0.48% by
weight, wet strengthening agent polyamine-polyamide-epichlorhydrin resin
(Kymene®) in a quantity of 0.36% by weight, and a natural CaCO3
in a quantity of 10% by weight. The quantities indicated are relative to
the cellulose mass. The thin matter, the pH value of which was adjusted
to about 7.5, was transported from the headbox to the screen on the paper
machine, after which the machine began to form sheets by dewatering the
web in the screen area of the paper machine. In the compaction area, the
web was dewatered further to reach a water content of 60% by weight
relative to the weight of the web. Further drying took place in the
drying area of the paper machine with heated drying cylinders. A base
paper having a grammage of 160 g/m2 and moisture of about 7% was
obtained.

[0042] The base paper is coated on both sides with a coating compound
consisting of a styrene acrylate binder, starch and a pigment mixture of
calcium carbonate and kaolin, each having a coating weight of 15
g/m2, it is then dried and finished with a calender. The material
obtained in this way is referred to in the following as base paper A,
which will be placed in the extruder for the subsequent lamination of the
metal coated film.

[0043] Base paper B was produced from eucalyptus pulp in the same way as
base paper A. However, in the pulp dispersion it also contains titanium
dioxide in such an amount that the base paper web still contains 10% by
weight TiO2 relative to the dry mass after production. This base
paper B was placed directly into an extruder for subsequent lamination of
the metal-coated film without applying any additional coating compound.

[0044] Both surfaces (front sides) of base papers A and B that were
intended to receive printing underwent irradiation with corona discharge
and then laminated in the laminator with a metallised, multilayer,
biaxially oriented polypropylene film (BOPP-Film, PZN, Vibac GmbH),
wherein a film of low density polyethylene (LDPE) was extruded between
the paper carrier material and the plastic film. The thickness of the
adhesive polyethylene film was 8 g/m2. The opposite side to the
printable side (rear side) of base papers A and B was coated in the
extruder with a polyethylene mixture of 30% by weight of a low density
polyethylene (LDPE, d=0.923 g/cm3) and 70% by weight of a high
density polyethylene (HDPE, d=0.964 g/cm3), having a coating weight
of 40 g/m2. The cooling cylinder was selected such that the
resulting surface of the rear side has a roughness of 0.9 μm measured
as an Rz value in accordance with DIN 4768. The materials obtained will
be referred to in the following as A1 and B1.

[0045] Then, the sides coated with the metallised film were coated with
the toner-absorbing coating compound and dried. The application quantity
of the coating compound was selected such that a dry coating of 0.5
g/m2 is created. The compositions of the coating compounds are
indicated in the following.

Coating Compound a

[0046] A dispersion of 3.0 of a conductive pigment (antimony-doped
titanium tin oxide FT-2000, manufacturer ISK ISHIHARA SANGYO KAISHA Ltd.,
Japan) was produced in 27 g of water and processed using a rotor-stator
mixing system (ULTRA-TURRAX® produced by IKA®, Germany) until the
average particle size of the pigment was 180 nm. 22.4 g of ethylene
acrylate dispersion MICHEM PRIME® 4990 R.E. was mixed with the
dispersion prepared in this way, 0.1 g wetting agent SURFYNOL® 440
and 47.5 g water were further added.

[0049] The two surfaces of base papers A and B intended to receive
printing were irradiated by corona discharge and then laminated with a
biaxially oriented polypropylene film TREFAN TND 35 (manufactured by
Treofan Germany GmbH & Co. KG). The rear sides of the papers were
extrusion coated with a polyethylene mixture as in the examples according
to the invention. The materials obtained will be referred to as A2 and B2
in the following.

[0050] The two surfaces of papers A2 and B2 intended for printing were
then coated with a toner-absorbing coating compound and dried. The
applied quantity of the coating composition was chosen so that a dry
coating of 0.5 g/m2 is obtained. The composition of the coating
compound is indicated in the following.

Coating Compound d (Comparison)

[0051] 1 g crosslinking agent Surfynol® 440 (available from Air
Products, Netherlands) and 72 g water were added to 27.9 g of an ethylene
acrylate dispersion MICHEM PRIME® 4990 R.E. (available from
Michelman, Belgium) having a polymer content of 35.7% by weight.

[0052] The recording materials obtained according to the invention and the
comparison samples were subjected to the tests described in the
following.

Surface Resistivity

[0053] Measured in accordance with DIN 53483 with a comb electrode,
readings measured in log(Ohm/cm)

Adhesion Test:

[0054] Two sheets of the carrier material, size DIN A4, are placed one on
top of the other and loaded with a 10 kg weight at 23° C. and 50%
RH. After 65 hours the sheets are separated manually and the
bond/adhesion is examined.

+: No adhesion, o: Slight adhesion, -: Strong adhesion

Toner Adhesion:

[0055] The recording materials are printed using an electrophotographic
printer of type HP® Indigo® 6000 and the adhesion of the toner is
evaluated at 23° C./50% RH by attaching and detaching a strip of
TESA 4104 adhesive tape.

[0058] In addition, printing tests were carried out with printers
IGen® 3 from XEROX® and NeXpress® from Kodak®, which work
with dry toners. The following table 2 shows the results of these tests
(averages for the 3 printers). Toner transfer to the recording sheet was
evaluated visually with reference to uniformity of homogeneously printed
colour surfaces, wherein "+" stands for good uniformity, "o" for slight
density fluctuations, and "-" stands for significant density fluctuations
in the reproduced image.

[0059] It was revealed that the images obtained when using the recording
materials according to the invention have an appearance comparable to the
appearance of silver halide photographs, and comparable haptics. Adhesion
of the toner to the surface is good in the recording materials according
to the invention, the sheets to not stick together, they do not charge
each other electrostatically, and they provide uniform toner transmission
when both dry toners and liquid toners are used. Shiny spots caused by
dripping of the oils used as auxiliary substances in the toners are
avoided definitively.